2021 Subaru Ascent BaseFACTORY OEM SERVICE PROCEDURE

Fuel Injector Circuit

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

G13866518Courtesy of SUBARU OF AMERICA, INC.
CAUTION:
  • Check or repair only faulty parts.
  • Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>General Description>PREPARATION TOOL>HOW TO USE CHECK BOARD .
  1. CHECK OPERATION OF EACH FUEL INJECTOR  .

    While cranking the engine, check each fuel injector emits operating sound. Use a sound scope or attach a screwdriver to the injector to listen to sounds for this check.

    Does the fuel injector emit operating sound?

    Yes  : Check the fuel pressure. Ref. to MECHANICAL (H4DOTC)>Fuel Pressure>INSPECTION .

    No  : Go to  2.

  2. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (OPEN)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Disconnect the connector from fuel injector.
    4. Measure the resistance of harness between ECM and fuel injector connector.

      Connector and terminal 

      #1 (E159) No. 1 - (E5) No. 1:

      #1 (E159) No. 2 - (E5) No. 2:

      #2 (E159) No. 9 - (E16) No. 1:

      #2 (E159) No. 10 - (E16) No. 2:

      #3 (E159) No. 17 - (E6) No. 1:

      #3 (E159) No. 18 - (E6) No. 2:

      #4 (E159) No. 25 - (E17) No. 1:

      #4 (E159) No. 26 - (E17) No. 2:

    Is the resistance less than 1 Ω?

    Yes  : Go to  3.

    No  : Repair the open circuit in harness between ECM and fuel injector connector.

  3. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (SHORT TO GROUND)  .

    Measure the resistance between fuel injector connector and engine ground.

    Connector and terminal 

    #1 (E5) No. 1 - Engine ground:

    #1 (E5) No. 2 - Engine ground:

    #2 (E16) No. 1 - Engine ground:

    #2 (E16) No. 2 - Engine ground:

    #3 (E6) No. 1 - Engine ground:

    #3 (E6) No. 2 - Engine ground:

    #4 (E17) No. 1 - Engine ground:

    #4 (E17) No. 2 - Engine ground:

    Is the resistance 1 MΩ or more?

    Yes  : Go to  4.

    No  : Repair the short circuit to ground in harness between ECM and fuel injector connector.

  4. CHECK EACH FUEL INJECTOR  .

    Check each fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>Fuel Injector>INSPECTION .

    Is the check result OK?

    Yes  : Repair the poor contact of ECM connector.

    No  : Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL INJECTOR .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Basic Diagnostic Procedure>PROCEDURE .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.